In recent years, research and development into effectively utilizing regenerative power generated by regenerative brakes included in trains for the purpose of energy saving and the like have been actively conducted. To effectively utilize regenerative power in a DC electrified section, there is a technology for dividing a traveling section of a train into a plurality of subsections, measuring electric currents and voltages of the overhead lines in the subsections using a plurality of current sensors and a plurality of voltage sensors, determining the on-rail state of the train, and calculating the value of the transmission voltage for the rectifiers in each substation (Patent Literature 1).